George peitchett



(No Model.)

G. PRITOHETTM FRICTION BLOCK FIRE ESCAPE.

Patented July 19, 1887.

Invenio 2".

UNITE STATES ATENT Orricn.

GEORGE PRITGHETT, OF BINGHAMTON, NEXV YORK.

FRICTION-BLOCK FIRE-ESCAPE.

SPECIFICATION forming part of Letters Patent No. 366,736, dated July 19, 1887.

(No model.)

To aZZ whom it may concern:

Be it known that I, GEORGE Pnrronn'rr, a citizen of the United States, residing at Bing hamton, in the county of Broome and State of New York, have invented certain new and useful Improvements in Friction-Block Fire- Escapes; andI do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertaius to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

Similar letters refer to similar parts throughout the several views.

My invention is that of afriction-block designed mainly for use as a fire-escape; but it may also be used for lowering heavy articles whenit is desired to retard the momentum, or for any purpose to which a friction-block is applicable.

In the accompanying drawings, Figure 1 is a View in outline of the completed block. Fig. 2 is a view of the working portions of the block removed from each other to show more clearly the detail of construction and method of use. Fig. 3 is an elevation of the block with one side removed to show the relative location of the several parts in the block.

The sides or frame of the block A A are plain solid pieces of plank bolted firmly through the blocks, and having the iron straps a a on them, with links and hooks a a, by which to hang it. Between the sides, near the middle, is the cylindrical block B, bolted fast to the sides A A. This block is cut with a spiral groove, 9, running round and round itcut deep enough to carry a rope of the size re quired for the use to which it is to be put. In use for a fireescape I have found a half inch rope aconvenient size. The spiral groove may be cut as many times around the block as required to produce the necessary friction. For ordinary use twice around is sufficient; but more may be added, and used or not, as heavier or lighter weights are to be lowered.

Above the cylindrical block B is a cap-block, O, with the under side concaved to fit the cylindrical block and grooved to correspond with the grooves in B and set close down on it, as

shown in Fig. 3. This forms closed recesses for the rope and prevents it being drawn out of place. Over the top of 0 there is a groove, h, in which the rope runs after it leaves the spiral groove of the cylindrical block, creating more frictionsurl'ace and carrying the rope clear from the round block, for it will be noticed that the cap-block is the segment of a circle of larger diameter than the block B. Above this is the head-block E, Fig. 3, with its underside concaved and grooved to fit over and correspond with the upper surface of 0.

Below the cylindrical block B is the footblock D, with its upper surface fitted to correspond with the under surface of B, and having the holesf f, through which the rope runs when it enters and leaves the block. \Vhen it is to be used fora fire-escape, the rope B has at one end, S, the stirrup, as shown in the drawings, Fig. 2, or may have attached asack, chair, or any device for supporting the person. The block being hung by the hooks a a, the weight to be lowered is attached to the rope at S, and as the rope is paid out by the person holding it at T the weight will slowly descend, the friction of the rope in the spiral groove greatly retarding its motion. I have found in practice that the descent of ten pounds at S maybe checked or entirely stopped by one pound of strength at T. So in use an adult person, with his weight on the rope and holding the rope at T in his own hands and paying it out, will have no difficulty in regulating his descent, and this without any risk of burning his hands on the rope. The form in which the block is hung and the rope run through the foot-block prevents the block from being thrown out of place orjerkiug, and permits a steady, uniform descent. If the persons dare not risk letting themselves down, the rope T may be thrown to the ground and held and paid out by another, and immediately run back when its weight is discharged. It is used in the same way for lowering dead weights, the weight being attached at S and .the rope paid out by the operator as the weight descends. The advantage which it possesses seems to be in the peculiar pressure secured upon the rope by its turning in the spiral grooves in the cylindrical block, by which much more friction results than in any form of friction-block known to me. The recesses for the rope, being cased in so that they are substantially circular holes, prevent any possibility of the rope throwing out or catching, and secures a steady strain.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

A friction-block constructed with flat sides, having hangers attached, in combination with a cylindrical block having a spiral groove cut around it, with concave blocks above and below it grooved to correspond with the grooves on it, the upper block having a groove on its upper surface and the lower one having holes through which the rope runs when it enters and leaves the block, all substantially as shown and described.

In testimony whereof I aflix my signature in presence of two witnesses.

GEORGE PRITOHETT. \Vitnesses:

A. L. PINE, J OHN LA GRANGE. 

